AlexLPD
23-02-2017, 04:23 AM
Hi to you all.
This is a new problem to me.
I will describe the system;
20TR condensr unit, two scroll compresor York brand.
20TR evaporator unit York.
220V , R22.
The condenser and evaporator are no far apart, a 10-25feet as much,in the same floor level.
Im the third tech, on the site, the past two, changue both compressors and they burned dow again.
So, long story short...they calll me to put to service two units describe as above... I didnt like much the scroll option, because this AC are in heavy loads and they usually work more than 18Hr at day (not on a single row)
We changue the tandem compressor othe the unit 3... for a mesa piston compresor of 20TR for R22... we changue the TXV for a brand new danfoss... It work like a champ...
We do the same thing on the number 2 unit... changue the tandem scroll compressor for a single coppeland discuss compressor.
So.. changue the TXV same model as before, alll welding as made with N2 purgue I personally inspect all the weldings to make sure they are clean.
We changue the old filter for a replaceable core of danfoss rated for 20TR, a core, a sigth glass (wasnt before).
High pressure N2 to make sure we didnt have any loss
I personally like to make a triple evacuattion process on this systems, so we did it, and the next day, add some refrigerant and ohhhh boy... things was awful ...
High pressure side 315 PSI
Low Pressure Side 95 PSI
Superheating -°F (Did not take sorry)
Subcooling -°F
Compressor amps (51.6A /52)
The sigth glass at this point it show not bubbles, but like foam fluid passing... So We leave it for the day..
The nex day... we remove some refrigerant the systems dont perform well... And for half of day we were seeking anything.
Until the sigthglass of the compressor got my attention...i cant see nothing, so a litte pinch to the contactor compressor show me, in deed the compresor carter was at the top of is capacity.
We remove the refrigerant, put a service hose and a ball valve at the end of the gear oil pum, and we pinch the contactor, at the first time we remove about 1.5L of oil (quite dirty, so I only assume this oil was in the system long before)
So, I think, we can back on duty... evac the system, add the refrigerant slowlly and this time, seems quite better:
High pressure side 290 PSI
Low Pressure Side 86 PSI
Superheating 28°F
Subcooling 20°F
Compressor amps (47.9A /52)
Ambient temp: 89.6°F - 32°C
Condenser Air temp: 114.8° - 46°C
Still one big problem remains... and this is; the unit is not cooling properly;
Evap Air Intake; 86°F 30°C
Evap Air Dischargue; 71.6F 22°C
So... we leave run for a while and after the compressor sigth glass was full again, stop the unit, recall the refrigerant, and remove some more oil...
It began to improve;
High pressure side 250 PSI
Low Pressure Side 70 PSI
Superheating 39°F
Subcooling 13°F
Compressor amps (42.9A /52)
Ambient temp: 91.4°F - 33°C
Condenser Air temp: 111.2° - 44°C
I get the next figures out the evaporator coil;
Evap Air Intake; 82.4°F 28°C
Evap Air Dischargue; 69.8 F 21°C
So even when we finally remove 3Lt of oil of the systems lines. The system dont give us more than 7°C of split between the inteake and the air send to the room.
Its important to me to solve this issue, because they are at least two more units in the same weird problem.
A weird thing happend to the end of the day today as yesterday, before we remove any oil; the pressures once the compressor is of, didnt equilibrate even at the 10min, for example if low is at 85, will move slow to 90 but not beyond, and high pressure will fall from 350Psi to 340 but not more...
Today has we removed some of the oil, the system balance whithin 3 or 4 minutes at the same static pressure (don have solenoid or anything else but the TXV)
But in the last test, the system dont balance...is like the TXV was clogged.
Due the fact the system was overfilled with oil, I think is safe to assume the condenser and the evaporator migth as well.
What is the proper thing to do? .. Leave the system recycle the oil ... Open the system and flush the oil ? This would do something ? as the system mixes up, oil and refrigerant?
Thanks for any insigth, sorry for any ortografic horror.
Have a nice day.
This is a new problem to me.
I will describe the system;
20TR condensr unit, two scroll compresor York brand.
20TR evaporator unit York.
220V , R22.
The condenser and evaporator are no far apart, a 10-25feet as much,in the same floor level.
Im the third tech, on the site, the past two, changue both compressors and they burned dow again.
So, long story short...they calll me to put to service two units describe as above... I didnt like much the scroll option, because this AC are in heavy loads and they usually work more than 18Hr at day (not on a single row)
We changue the tandem compressor othe the unit 3... for a mesa piston compresor of 20TR for R22... we changue the TXV for a brand new danfoss... It work like a champ...
We do the same thing on the number 2 unit... changue the tandem scroll compressor for a single coppeland discuss compressor.
So.. changue the TXV same model as before, alll welding as made with N2 purgue I personally inspect all the weldings to make sure they are clean.
We changue the old filter for a replaceable core of danfoss rated for 20TR, a core, a sigth glass (wasnt before).
High pressure N2 to make sure we didnt have any loss
I personally like to make a triple evacuattion process on this systems, so we did it, and the next day, add some refrigerant and ohhhh boy... things was awful ...
High pressure side 315 PSI
Low Pressure Side 95 PSI
Superheating -°F (Did not take sorry)
Subcooling -°F
Compressor amps (51.6A /52)
The sigth glass at this point it show not bubbles, but like foam fluid passing... So We leave it for the day..
The nex day... we remove some refrigerant the systems dont perform well... And for half of day we were seeking anything.
Until the sigthglass of the compressor got my attention...i cant see nothing, so a litte pinch to the contactor compressor show me, in deed the compresor carter was at the top of is capacity.
We remove the refrigerant, put a service hose and a ball valve at the end of the gear oil pum, and we pinch the contactor, at the first time we remove about 1.5L of oil (quite dirty, so I only assume this oil was in the system long before)
So, I think, we can back on duty... evac the system, add the refrigerant slowlly and this time, seems quite better:
High pressure side 290 PSI
Low Pressure Side 86 PSI
Superheating 28°F
Subcooling 20°F
Compressor amps (47.9A /52)
Ambient temp: 89.6°F - 32°C
Condenser Air temp: 114.8° - 46°C
Still one big problem remains... and this is; the unit is not cooling properly;
Evap Air Intake; 86°F 30°C
Evap Air Dischargue; 71.6F 22°C
So... we leave run for a while and after the compressor sigth glass was full again, stop the unit, recall the refrigerant, and remove some more oil...
It began to improve;
High pressure side 250 PSI
Low Pressure Side 70 PSI
Superheating 39°F
Subcooling 13°F
Compressor amps (42.9A /52)
Ambient temp: 91.4°F - 33°C
Condenser Air temp: 111.2° - 44°C
I get the next figures out the evaporator coil;
Evap Air Intake; 82.4°F 28°C
Evap Air Dischargue; 69.8 F 21°C
So even when we finally remove 3Lt of oil of the systems lines. The system dont give us more than 7°C of split between the inteake and the air send to the room.
Its important to me to solve this issue, because they are at least two more units in the same weird problem.
A weird thing happend to the end of the day today as yesterday, before we remove any oil; the pressures once the compressor is of, didnt equilibrate even at the 10min, for example if low is at 85, will move slow to 90 but not beyond, and high pressure will fall from 350Psi to 340 but not more...
Today has we removed some of the oil, the system balance whithin 3 or 4 minutes at the same static pressure (don have solenoid or anything else but the TXV)
But in the last test, the system dont balance...is like the TXV was clogged.
Due the fact the system was overfilled with oil, I think is safe to assume the condenser and the evaporator migth as well.
What is the proper thing to do? .. Leave the system recycle the oil ... Open the system and flush the oil ? This would do something ? as the system mixes up, oil and refrigerant?
Thanks for any insigth, sorry for any ortografic horror.
Have a nice day.